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| United States Patent |
5,656,198
|
|
Naito
, et al.
|
August 12, 1997
|
Tolan compound and liquid crystal composition containing the same
Abstract
A novel tolan compound of the formula (I):
##STR1##
wherein A is a substituted or unsubstituted cyclohexyl or phenyl group; B
is --CO--O-- or --O--CO--; X is a hydrogen atom, a halogen atom, a cyano
group, a C.sub.1 -C.sub.10 alkyl group, or a C.sub.1 -C.sub.10 alkoxy
group; Y is a hydrogen atom or a halogen atom; and m and n are an integer
of 0 or 1, provided that m+n=0 or 1. The tolan compound can raise the N-I
point and increase the double refractive index (.DELTA.n) of liquid
crystal compositions. The liquid crystal composition containing this tolan
compound has excellent characteristics as a liquid crystal material, and
the liquid crystal display device using this liquid crystal composition
has a wide temperature range and a wide visible angle and can be operated
at a low driving voltage.
| Inventors:
|
Naito; Tomijiro (Asaka, JP);
Sakamaki; Yumiko (Sayama, JP);
Niino; Katsuji (Kawanishi, JP);
Yamamoto; Kikuo (Habikino, JP)
|
| Assignee:
|
Citizen Watch Co., Ltd. (Tokyo, JP)
|
| Appl. No.:
|
628028 |
| Filed:
|
April 4, 1996 |
Foreign Application Priority Data
| Apr 07, 1995[JP] | 7-082686 |
| Aug 24, 1995[JP] | 7-216027 |
| Aug 24, 1995[JP] | 7-216028 |
| Dec 21, 1995[JP] | 7-333430 |
| Dec 25, 1995[JP] | 7-337119 |
| Current U.S. Class: |
252/299.01; 252/299.63; 252/299.66; 252/299.67; 349/182 |
| Intern'l Class: |
C09K 019/52; C09K 019/30; G02F 001/13 |
| Field of Search: |
252/299.01,299.63,299.66,299.67
359/103
349/182
428/1
|
References Cited
Other References
Tinh et al., "Synthesis and Mesomorphic properties of the Homologous Series
of 4-Alkyl or Alkory-4'-Bromo or Cyanotolanes", Mol. Cryst. Liq. Cryst.,
1980, vol. 62, pp. 125-140.
|
Primary Examiner: Wu; Shean C.
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier & Neustadt, P.C.
Claims
What is claimed is:
1. A tolan compound represented by the following formula (Ia):
##STR55##
wherein R.sub.2 represents a hydrogen atom or an alkyl group having 1-10
carbon atoms; X.sub.1 represents a halogen atom, an alkyl group having
1-10 carbon atoms, or an alkoxy group having 1-10 carbon atoms; Y
represents a hydrogen atom or a halogen atom; and m1 and n1 are
individually an integer of 0 or 1, provided that m1+n1 is 1.
2. A tolan compound represented by the following formula (Ib):
##STR56##
wherein R.sub.2 represents a hydrogen atom or an alkyl group having 1-10
carbon atoms and X.sub.2 represents a halogen atom, a cyano group, or an
alkoxy group having 1-10 carbon atoms.
3. A tolan compound represented by the following formula
##STR57##
wherein R.sub.1 represents a hydrogen atom, a halogen atom, a cyano group,
an alkyl group having 1-10 carbon atoms, or an alkoxy group having 1-10
carbon atoms; X.sub.3 represents a hydrogen atom or an alkyl group having
1-10 carbon atoms; and Z.sub.1 and Z.sub.2 represent individually a
hydrogen atom or a halogen atom.
4. A liquid crystal composition comprising at least one tolan compound
defined in claim 1.
5. A liquid crystal composition comprising at least one tolan compound
defined in claim 2.
6. A liquid crystal composition comprising at least one tolan compound
defined in claim 3.
7. A liquid crystal display device using the liquid crystal composition
defined in claim 4.
8. A liquid crystal display device using the liquid crystal composition
defined in claim 5.
9. A liquid crystal display device using the liquid crystal composition
defined in claim 6.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a tolan compound which is useful as a
liquid crystal material and to a liquid crystal composition containing
this tolan compound.
2. Discussion of the Background
A liquid crystal display device has been widely utilized for a watch, an
electronic calculator as well as a word processor, a television set, etc.
Of these liquid crystal display devices, particularly frequently used is a
liquid crystal display device which utilized optical anisotropy and
dielectric anisotropy of a liquid crystal material.
A wide liquid crystal temperature range, a low viscosity to ensure a rapid
electro-optical response rate, a suitable double refractive index
(.DELTA.n) to provide a wide visual scope and a high contrast, a large
dielectric anisotropy (.DELTA..epsilon.) to ensure a low driving voltage,
and the characteristics to be chemically and optically stable are given as
the characteristics required for a liquid crystal material to be used for
liquid crystal display devices.
Liquid crystal compositions presently used are usually prepared by mixing a
compound having a liquid crystal phase near room temperatures and a
compound having a liquid crystal phase at temperatures higher than room
temperatures. In order for a liquid crystal display device to be used
outdoor the liquid crystal must be stable in the temperature range of
-40.degree. C. to 90.degree. C. In addition, because of the temperature
dependency of optical anisotropy and dielectric anisotropy, that is,
because of occurrence of sudden change near the N-I point (nematic
anisotropy phase transfer temperature), it is necessary to use a liquid
crystal material with a high N-I point.
Furthermore, to ensure a wide visual angle and a high contrast the
retardation of liquid crystal phase, .DELTA.n.multidot.d, wherein .DELTA.n
is the double refractive index of the liquid crystal material and d is the
thickness of liquid crystal layer, must be optimized. However, because the
thickness of liquid crystal layer (d) is limited to a certain range and a
high response rate is required for liquid crystal display devices actually
used, the thickness of liquid crystal layer (d) tends to be thin. Because
of this reason, a liquid crystal materials with a large double refractive
index (.DELTA.n) is required.
A driving voltage is dependent on a threshold voltage Vth, whereas the
threshold voltage Vth is inversely proportional to the square root of
dielectric anisotropy (.DELTA..epsilon.). Accordingly, the threshold
voltage Vth can be kept low when a liquid crystal material with a positive
value of dielectric anisotropy (.DELTA..epsilon.) is used.
Although various liquid crystal compounds have been developed and put on
use up to the present time, these is no single liquid crystal compound
satisfying all the characteristics mentioned above. Therefore, in
practice, several kinds of liquid crystal compounds having different
characteristics or non-liquid crystal compounds are mixed and used. Such
mixtures, however, are not necessarily satisfactory.
4-Alkyl-4'-alkoxytolan (German Patent No. 2226376) and
4-alkyl-4'-fuluorotolan (Japanese Patent Application Laid-Open No.
260031/1986) are examples of known tolan compounds which are used mixed
for the above-mentioned purpose. The mixtures of these tolan compounds,
however, are not necessarily satisfactory.
As described above, in spite of various studies in the past on liquid
crystal compositions no material which sufficiently satisfies all above
characteristics has been found. Each compound used for liquid crystal
materials has merits and demerits in its characteristics. In addition, the
degree of the above required characteristics is different depending on the
liquid crystal display device. The development of a novel liquid crystal
compound and a liquid crystal additive which can provide characteristics
depending on the intended object of a liquid crystal display device has
been desired. Accordingly, an object of the present invention is to
provide a novel tolan compound which, if added to a liquid crystal
composition, can raise the N-I point and increase the double refractive
index (.DELTA.n) of the liquid crystal composition. Another object of the
present invention is to provide such a liquid crystal composition
comprising this novel tolan compound.
SUMMARY OF THE INVENTION
Accordingly, a specific object of the present invention is to provide a
tolan compound represented by the following formula (I):
##STR2##
wherein A represents a cyclohexyl group which may be substituted by an
alkyl group having 1-10 carbon atoms, or a group represented by the
following formula,
##STR3##
wherein R.sub.1 represents a hydrogen atom, a halogen atom, a cyano group,
an alkyl group having 1-10 carbon atoms, or an alkoxy group having 1-10
carbon atoms; and Z.sub.1 and Z.sub.2 represent a hydrogen atom or a
halogen atom;
B represents a group,
##STR4##
X represents a hydrogen atom, a halogen atom, a cyano group, an alkyl
group having 1-10 carbon atoms, or an alkoxy group having 1-10 carbon
atoms;
Y represents a hydrogen atom or a halogen atom; and
m and n is an integer of 0 or 1, provided that m+n is 0 or 1; provided
further that when A is a cyclohexyl group which may be substituted by an
alkyl group having 1-10 carbon atoms and m+n is 0, X is a halogen atom, a
cyano group, or an alkoxy group having 1-10 carbon atoms.
Another object of the present invention is to provide a liquid crystal
composition comprising at least one tolan compound represented by the
above formula (I).
A still another object of the present invention is to provide liquid
crystal display device using the liquid crystal composition comprising at
least one tolan compound represented by the above formula (I).
Other objects, features and advantages of the invention will hereinafter
become more readily apparent from the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 1.
FIG. 2 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 2.
FIG. 3 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 3.
FIG. 4 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 4.
FIG. 5 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 5.
FIG. 6 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 6.
FIG. 7 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 7.
FIG. 8 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 8.
FIG. 9 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 9.
FIG. 10 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 10.
FIG. 11 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 11.
FIG. 12 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 12.
FIG. 13 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 13.
FIG. 14 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 27.
FIG. 15 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 28.
FIG. 16 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 29.
FIG. 17 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 30.
FIG. 18 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 35.
FIG. 19 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 36.
FIG. 20 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 37.
FIG. 21 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 38.
FIG. 22 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 39.
FIG. 23 is a diagram showing an infrared absorption spectrum of the tolan
compound prepared in Example 40.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The halogen atom which is present in the tolan compound of the present
invention as a substituent is preferably fluorine atom in view of the
viscosity and specific resistance of the tolan compound, although chlorine
atom and bromine atom are acceptable.
The tolan compound of the present invention may be mixed with various
liquid crystal compounds to produce liquid crystal compositions. Esters,
cyclohexylphenyl compounds, biphenyl compounds, pyrimidine compounds,
dioxane compounds, tolan compounds (other than tolan compounds of the
present invention) are given as the liquid crystalline compounds which can
be mixed with the tolan compound of the present invention. A mixture of
two or more of these liquid crystal compounds may be further mixed with
the tolan compound of the present invention.
As mentioned above, the liquid crystal composition comprising the tolan
compound of the present invention has excellent characteristics as a
liquid crystal material, and the liquid crystal display device using this
liquid crystal composition has a wide temperature range and a wide visible
angle and can be operated at a low driving voltage.
The amount of the tolan compound of the present invention to be
incorporated in the liquid crystal composition varies depending on the
types and amounts of other liquid crystalline compounds and cannot be
generically determined. Usually, an amount of 1-50% by weight is
preferable, with a more preferable amount being 3-20% by weight.
The compound (I) of the present invention can be grouped into the following
compounds (Ia) to (Ic).
##STR5##
wherein R.sub.2 represents a hydrogen atom or an alkyl group having 1-10
carbon atoms; X.sub.1 represents a halogen atom, an alkyl group having
1-10 carbon atoms, or an alkoxy group having 1-10 carbon atoms; X.sub.2
represents a halogen atom, a cyano group, or an alkoxy group having 1-10
carbon atoms; X.sub.3 represents a hydrogen atom or an alkyl group having
1-10 carbon atoms; Z.sub.1 and Z.sub.2 individually represent a hydrogen
atom or a halogen atom; and m1 and n1 is an integer of 0 or 1, provided
that m1+n1 is 0 or 1; and R.sub.1 has the same meaning as defined above.
The tolan compound (Ia) of the present invention is an excellent compound
which, when added to a liquid crystal composition, can increase the N-I
point and double refractive index (.DELTA.n) of the liquid crystal
composition.
The tolan compound (Ib) of the present invention is an excellent compound
which, when added to a liquid crystal composition, can increase the N-I
point and double refractive index (.DELTA.n) without significantly
changing the viscosity .eta. and threshold voltage Vth of the liquid
crystal composition.
The tolan compound (Ic) of the present invention is an excellent compound
which, when added to a liquid crystal composition, can increase the N-I
point and double refractive index (.DELTA.n) of the liquid crystal
composition. In addition, the tolan compound (Ic) having a cyano group or
a halogen atom for the terminal group R.sub.1 has a decreased threshold
voltage Vth.
The processes for preparing the tolan compounds of the present invention
will now be illustrated.
Process 1:
The compound (Ia) can be prepared by reacting an acid chloride (a) and a
substituted phenol (b) in an inert organic solvent such as pyridine;
recrystallizing, washing, and drying the reaction product to produce an
ester (c); reacting the ester (c) with a phenyl acetylene compound (d) in
the presence of triethylamine; and washing with water, drying, and
recrystallizing the resulting reaction product according to the following
reaction scheme.
##STR6##
wherein R.sub.2, X.sub.1, Y, m1 and n1 have the same meaning defined
above.
Process 2:
The compound (Ib) can be prepared in the similar manner as in Process 1
according to the following reaction scheme.
##STR7##
wherein R.sub.2 and X.sub.2 have the same meaning defined above. Process
3:
The compound (Ic) can be prepared by reacting bromobenzoic acid (e) and a
halogenating agent such as thionyl chloride to obtain an acid chloride
(f); reacting the acid chloride (f) with a substituted phenol (g) in an
inert organic solvent such as pyridine; recrystallizing, washing with
water, and drying the reaction product to produce an ester of the
bromobenzoic acid and the substituted phenol (h); reacting the ester (h)
with an alkyl phenyl acetylene (i) in the presence of triethylamine; and
washing, drying, and recrystallizing the resulting reaction product
according to the following reaction scheme.
##STR8##
wherein R.sub.1, X.sub.3, Z.sub.1, and Z.sub.2 have the same meaning
defined above.
Other features of the invention will become apparent in the course of the
following description of the exemplary embodiments which are given for
illustration of the invention and are not intended to be limiting thereof.
In the examples below, the threshold voltage Vth was measured on the
liquid crystal composition mounted on a TN-type liquid crystal display
device with a cell thickness of 9 .mu.m.
EXAMPLES
Example 1
120 g of thionyl chloride was added to 100 g of 4-bromobenzoic acid and the
mixture was heated at 90.degree. C. while stirring for 6 hours. After the
reaction, an excess amount of thionyl chloride was removed by evaporation.
85 g of bromobenzoic acid chloride was obtained at a distillation
temperature range of 190.degree.-200.degree. C. by vacuum distillation at
about 20 mmHg. A solution prepared from 50 g of 3,4-difluorophenol, 150 ml
of dimethylformamide, and 31 g of pyridine was added dropwise to the
bromobenzoic acid chloride over about one hour while stirring at a
temperature below 30.degree. C. The mixture was then heated to 70.degree.
C. and stirred for 10 hours, and poured into a 10-fold amount of water to
produce crystals. The crystals were collected by filtration, washed with
dilute HCl and then water, dried in vacuum at 40.degree. C., and
recrystallized from ethyl acetate to obtain 50 g of 3,4-difluorophenyl
4-bromobenzoate. To this were added 25 g of 4-n-propylphenylacetylene,
0.11 g of bis(triphenylphosphine)palladium(II) chloride, 0.12 g of copper
iodide, 0.96 g of triphenylphosphine, and 320 ml of triethylamine,
followed by stirring for 10 hours while heating at 90.degree. C. After the
reaction, the reaction product was poured into a 10-fold amount of water
to produce crystals. The crystals were collected by filtration, washed
with water, dried in vacuum at 40.degree. C., and recrystallized from a
mixed solvent of ethyl acetate and methanol to obtain 43 g of
3,4-difluorophenyl 4-[2-(4-propylphenyl)ethynyl]benzoate of the following
formula.
##STR9##
This compound had a nematic liquid crystal phase, a C-N point
(crystal-nematic phase transfer temperature) of 106.9.degree. C., and an
N-I point of 168.5.degree. C. The IR spectrum of this compound is shown in
FIG. 1.
Example 2
43 g of 3,4-difluorophenyl 4-[2-(4-ethylphenyl)ethynyl]benzoate of the
following formula was prepared in the same manner as in Example 1, except
for using 26 g of 4-n-ethylphenylacetylene instead of 25 g of
4-n-propylphenylacetylene.
##STR10##
This compound had a nematic liquid crystal phase, a C-N point
(crystal-nematic phase transfer temperature) of 113.degree. C., and an N-I
point of 162.degree. C. The IR spectrum of this compound is shown in FIG.
2.
Example 3
43 g of 3,4-difluorophenyl 4-[2-(4-butylphenyl)ethylnyl]benzoate of the
following formula was prepared in the same manner as in Example 1, except
for using 24 g of 4-n-butylphenylacetylene instead of 25 g of
4-n-propylphenylacetylene.
##STR11##
This compound had a liquid crystal phase, a C-S point (crystal-smectic
phase transfer temperature) of 89.degree. C., an S-N point
(smectic-nematic phase transfer temperature) of 115.degree. C., and an N-I
point of 157.degree. C. The IR spectrum of this compound is shown in FIG.
3.
Example 4
43 g of 3,4-difluorophenyl 4-[2-(4-pentylphenyl)ethynyl]benzoate of the
following formula was prepared in the same manner as in Example 1, except
for using 23 g of 4-n-pentylphenylacetylene instead of 25 g of
4-n-propylphenylacetylene.
##STR12##
This compound had a liquid crystal phase, a C-S point (crystal-smectic
phase transfer temperature) of 88.degree. C., an S-N point
(smectic-nematic phase transfer temperature) of 122.degree. C., and an N-I
point of 160.degree. C. The IR spectrum of this compound is shown in FIG.
4.
Example 5
38 g of 4-fluorophenyl 4-[2-(4-propylphenyl)ethynyl]benzoate of the
following formula was prepared in the same manner as in Example 1, except
for using 43g of 4-fluorophenol instead of 50 g of 3,4-difluorophenol.
##STR13##
This compound had a nematic liquid crystal phase, a C-N point
(crystal-nematic phase transfer temperature) of 131.degree. C., and an N-I
point of 199.degree. C. The IR spectrum of this compound is shown in FIG.
5.
Example 6
40 g of 4-cyanophenyl 4-[2-(4-propylphenyl)ethynyl]benzoate of the
following formula was prepared in the same manner as in Example 1, except
for using 46 g of 4-cyanophenol instead of 50 g of 3,4-difluorophenol.
##STR14##
This compound had a nematic liquid crystal phase, a C-N point
(crystal-nematic phase transfer temperature) of 140.degree. C., and an N-I
point of 268.degree. C. The IR spectrum of this compound is shown in FIG.
6.
Example 7
45 g of 4 -ethoxyphenyl 4-[2-(4-propylphenyl)ethynyl]benzoate of the
following formula was prepared in the same manner as in Example 1, except
for using 53 g of 4-ethoxyphenol instead of 50 g of 3,4-difluorophenol.
##STR15##
This compound had a nematic liquid crystal phase, a C-N point
(crystal-nematic phase transfer temperature) of 113.degree. C., and an N-I
point of 254.degree. C. The IR spectrum of this compound is shown in FIG.
7.
Example 8
44 g of 4-propylphenyl 4-[2-(4-propylphenyl)ethynyl]benzoate of the
following formula was prepared in the same manner as in Example 1, except
for using 52 g of 4-propylphenol instead of 50 g of 3,4-difluorophenol.
##STR16##
This compound had a nematic liquid crystal phase, a C-N point
(crystal-nematic phase transfer temperature) of 130.degree. C., and an N-I
point of 211.degree. C. The IR spectrum of this compound is shown in FIG.
8.
Example 9
35 g of 4-methylphenyl 4-[2-(4-propylphenyl)ethynyl]benzoate of the
following formula was prepared in the same manner as in Example 1, except
for using 41 g of 4-methylphenol instead of 50 g of 3,4-difluorophenol.
##STR17##
This compound had a nematic liquid crystal phase, a C-N point
(crystal-nematic phase transfer temperature) of 124.degree. C., and an N-I
point of 219.degree. C. The IR spectrum of this compound is shown in FIG.
9.
Example 10
34 g of 4-methylphenyl 4-[2-(4-ethylphenyl)-ethynyl]benzoate of the
following formula was prepared in the same manner as in Example 1, except
for using 41 g of 4-methylphenol instead of 50 g of 3,4-difluorophenol and
26 g of 4-ethylphenyl acetylene instead of 25 g of 4-n-propylphenyl
acetylene.
##STR18##
This compound had a nematic liquid crystal phase, a C-N point
(crystal-nematic phase transfer temperature) of 121.degree. C., and an N-I
point of 215.degree. C. The IR spectrum of this compound is shown in FIG.
10.
Example 11
34 g of 4-methylphenyl 4-[2-(4-butylphenyl)-ethynyl]benzoate of the
following formula was prepared in the same manner as in Example 1, except
for using 41 g of 4-methylphenol instead of 50 g of 3,4-difluorophenol and
24 g of 4-n-butylphenyl acetylene instead of 25 of 4-n-propylphenyl
acetylene.
##STR19##
This compound had a nematic liquid crystal phase, a C-N point
(crystal-nematic phase transfer temperature) of 107.degree. C., and an N-I
point of 203.degree. C. The IR spectrum of this compound is shown in FIG.
11.
Example 12
33 g of 4-methylphenyl 4-[2-(4-pentylphenyl)ethynyl]benzoate of the
following formula was prepared in the same manner as in Example 1, except
for using 41 g of 4-methylphenol instead of 50 g of 3,4-difluorophenol and
23 g of 4-n-pentylphenyl acetylene instead of 25 g of 4-n-propylphenyl
acetylene.
##STR20##
This compound had a nematic liquid crystal phase, a C-N point
(crystal-nematic phase transfer temperature) of 110.degree. C., and an N-I
point of 202.degree. C. The IR spectrum of this compound is shown in FIG.
12.
Example 13
35 g of 3-fluoro-4-cyanophenyl 4-[2-(4-propylphenyl)ethynyl]benzoate of the
following formula was prepared in the same manner as in Example 1, except
for using 51 g of 3-fluoro-4-cyanophenol instead of 50 g of
3,4-difluorophenol.
##STR21##
This compound had a nematic liquid crystal phase, a C-N point
(crystal-nematic phase transfer temperature) of 87.degree. C., and an N-I
point of 229.degree. C. The IR spectrum of this compound is shown in FIG.
13.
Example 14
A liquid crystal composition was prepared by blending 90 parts by weight of
a commercially available nematic liquid crystal composition, ZLI-1132.TM.
(a product of Merck), and 10 parts of the tolan compound of the present
invention prepared in Example 1. The properties of the liquid crystal
composition were measured and the composition was found to have the
following properties:
NI point: 78.0.degree. C.
.DELTA.n: 0.153
Viscosity: 30.5 cP
Vth: 1.78 V
The properties of the liquid crystal composition, ZLI-1132.TM., were as
follows:
NI point: 72.degree. C.
.DELTA.n: 0.138
Viscosity: 27.9 cP
Vth: 1.83 V
Examples 15-26
Liquid crystal compositions were prepared in the same manner as in Example
14 from 90 parts by weight of the liquid crystal composition ZLI-1132.TM.
and 10 parts by weight of the tolan compounds of the present invention
prepared in Examples 2-13. The properties of these liquid crystal
compositions and the chemical formulas of the tolan compounds of the
present invention used for these compositions are given in Tables 1 and 2.
These tables include the corresponding data for the liquid crystal
composition of Example 14 and the properties of the liquid crystal
composition ZLI-1132.TM..
TABLE 1
__________________________________________________________________________
Viscosity
N-I Point
.DELTA.n
(cP) Vth (V)
Example No.
Chemical Formula (.degree.C.)
at 25.degree. C.
at 20.degree. C.
at 25.degree. C.
__________________________________________________________________________
14
##STR22## 78.0 0.153
30.5 1.78
15
##STR23## 78.3 0.153
30.2 1.70
16
##STR24## 78.5 0.148
31.2 1.65
17
##STR25## 79.1 0.151
31.3 1.72
18
##STR26## 78.5 0.154
29.9 1.80
19
##STR27## 79.7 0.150
31.4 1.82
20
##STR28## 84.8 0.157
31.1 1.91
__________________________________________________________________________
TABLE 2
__________________________________________________________________________
Viscosity
N-I Point
.DELTA.n
(cP) Vth (V)
Example No.
Chemical Formula (.degree.C.)
at 25.degree. C.
at 20.degree. C.
at 25.degree. C.
__________________________________________________________________________
21
##STR29## 81.9 0.155
29.5 1.87
22
##STR30## 83.6 0.155
30.3 1.85
23
##STR31## 83.5 0.157
30.0 1.84
24
##STR32## 82.4 0.155
30.0 1.86
25
##STR33## 82.6 0.153
30.3 1.89
26
##STR34## 84.1 0.159
34.7 1.73
ZLI-1132 72.0 0.138
27.9 1.83
__________________________________________________________________________
As can be seen from Tables 1 and 2, the tolan compounds of the present
invention increase the N-I point and double refractive index (.DELTA.n) of
the liquid crystal compositions which contain these compounds, and some of
these compounds decrease the threshold voltage Vth of such compositions.
The tolan compounds of the present invention are thus effective as a
component for liquid crystal compositions.
Example 27
20 g of 4-bromophenylphenol, 150 ml of dimethylformamide, and 6 g of
pyridine were dissolved 15 g of commercially available
trans-4-n-butylcyclohexanone carboxylic acid chloride was added dropwise
to the solution and the mixture was heated while stirring. The reaction
mixture was poured into water to produce crystals. The crystals were
collected by filtration, washed with dilute HCl and then water, dried in
vacuum, and recrystallized from a mixed solvent of ethyl acetate and
methanol to obtain 20 g of 4-bromo-4'-biphenyl trans-4-n-butylcyclohexane
carboxylate. To this were added 7 g of 4-ethylphenyl-acetylene, 0.03 g of
bis(triphenylphosphine)-palladium(II) chloride, 0.04 g of copper iodide,
0.3 g of triphenylphosphine, and 100 ml of triethylamine, and the mixture
was heated while stirring. After the reaction, the reaction product was
poured into water and neutralized with HCl to produce crystals. The
crystals were collected by filtration, washed with water, dried in vacuum,
and recrystallized from a mixed solvent of ethyl acetate and methanol to
obtain 12.5 g of a compound having the following formula.
##STR35##
This compound had a nematic liquid crystal phase, a C-N point
(crystal-nematic phase transfer temperature) of 213.degree. C., and an N-I
point of 226.degree. C. The IR spectrum of this compound is shown in FIG.
14.
Example 28
13 g of a compound having the following formula was prepared in the same
manner as in Example 27, except for using 8 g of 4-n-propylphenyl
acetylene instead of 7 g of 4-ethylphenyl acetylene.
##STR36##
This compound had a nematic liquid crystal phase, a C-N point of
209.degree. C., and an N-I point of 224.degree. C. The IR spectrum of this
compound is shown in FIG. 15.
Example 29
12 g of a compound having the following formula was prepared in the same
manner as in Example 27, except for using 6 g of 4-fluorophenyl acetylene
instead of 7 g of 4-ethylphenyl acetylene.
##STR37##
This compound had a nematic liquid crystal phase, a C-N point of
209.degree. C., and an N-I point of 237.degree. C. The IR spectrum of this
compound is shown in FIG. 16.
Example 30
14 g of a compound having the following formula was prepared in the same
manner as in Example 27, except for using 14 g of 4-bromophenol instead of
20 g of 4-bromophenylphenol and further using 11 g of 4-n-heptylbiphenyl
acetylene instead of 7 g of 4-ethylphenyl acetylene.
##STR38##
This compound had a nematic liquid crystal phase, a C-N point of
207.degree. C., and an N-I point of 302.degree. C. The IR spectrum of this
compound is shown in FIG. 17.
Example 31
A liquid crystal composition was prepared by blending 95 parts by weight of
a commercially available nematic liquid crystal composition, ZLI-1132.TM.
(a product of Merck), and 5 parts by weight of the tolan compound of the
present invention prepared in Example 27. The properties of the liquid
crystal composition are shown in Table 3.
The properties of the liquid crystal composition, ZLI-1132.TM., were as
follows:
NI point: 72.degree. C.
.DELTA.n: 0.138
Viscosity: 27.9 cp
Vth: 1.83 V
Examples 32-34
Liquid crystal compositions were prepared in the same manner as in Example
31 from 95 parts by weight of the liquid crystal composition ZLI-1132.TM.
and 5 parts by weight of the tolan compounds of the present invention
prepared in Examples 28-30. The properties of these liquid crystal
compositions and the chemical formulas of the tolan compounds of the
present invention used for these compositions are given in Table 3, which
includes the corresponding data for the liquid Crystal composition of
Example 31and the properties of the liquid crystal composition
ZLI-1132.TM..
As can be seen from Table 3, when added in a small amount the tolan
compounds of the present invention remarkably increase the N-I point and
double refractive index (.DELTA.n) of the liquid crystal compounds which
contain these compounds.
TABLE 3
__________________________________________________________________________
Viscosity
N-I Point
.DELTA.n
(cP) Vth (V)
Example No.
Chemical Formula (.degree.C.)
at 25.degree. C.
at 20.degree. C.
at 25.degree. C.
__________________________________________________________________________
31
##STR39## 81.0 0.146
30.3 1.86
32
##STR40## 80.9 0.146
29.4 1.87
33
##STR41## 80.4 0.146
29.7 1.85
34
##STR42## 80.3 0.146
30.3 1.89
ZLI-1132 72.0 0.138
27.9 1.83
__________________________________________________________________________
Example 35
26 g of 4-bromophenol, 100 ml of dimethylformamide, and 13 g of pyridine
were dissolved. 31 g of commercially available trans-4-n-butylcyclohexane
carboxylic acid chloride was added dropwise to the solution and the
mixture was heated while stirring. The reaction mixture was poured into
water to produce crystals. The crystals were collected by filtration,
washed with dilute HCl and then water, dried in vacuum, and recrystallized
from a mixed solvent of ethyl acetate and methanol to obtain 44 g of
4-bromophenyl trans-4-n-butylcyclohexane carboxylate. To this were added
20 g of 4-ethoxyphenyl acetylene, 0.09 g of
bis(triphenylphosphine)-palladium(II) chloride, 0.1 g of copper iodide,
0.79 g of triphenylphosphine, and 260 ml of triethylamine, and the mixture
was heated while stirring. After the reaction, the reaction product was
poured into water and neutralized with HCl to produce crystals. The
crystals were collected by filtration, washed with water, dried in vacuum,
and recrystallized from a mixed solvent of ethyl acetate and methanol to
obtain 40 g of a compound having the following formula.
##STR43##
This compound had a nematic liquid crystal phase, a C-N point
(crystal-nematic phase transfer temperature) of 99.degree. C., and an N-I
point of 252.degree. C. The IR spectrum of this compound is shown in FIG.
18.
Example 36
36 g of a compound having the following formula was prepared in the same
manner as in Example 35, except for using 29 g of
trans-4-propylcyclohexane carboxylic acid chloride instead of 31 g of
trans-4-n-butylcyclohexane carboxylic acid chloride and further using 16 g
of 4-fluorophenyl acetylene instead of 20 g of 4-ethoxyphenyl acetylene.
##STR44##
This compound had a nematic liquid crystal phase, a C-N point of
119.degree. C., and an N-I point of 209.degree. C. The IR spectrum of this
compound is shown in FIG. 19.
Example 37
38 g of a compound having the following formula was prepared in the same
manner as in Example 35, except for using 29 g of
trans-4-n-propylcyclohexane carboxylic acid chloride instead of 31 g of
trans-4-n-butylcyclohexane carboxylic acid chloride.
##STR45##
This compound had a nematic liquid crystal phase, a C-N point of
107.degree. C., and an N-I point of 260.degree. C. The IR spectrum of this
compound is shown in FIG. 20.
Example 38
37 g of a compound having the following formula was prepared in the same
manner as in Example 35, except for using 28 g of
trans-4-n-ethylcyclohexane carboxylic acid chloride instead of 31 g of
trans-4-n-butylcyclohexane carboxylic acid chloride.
##STR46##
This compound had a nematic liquid crystal phase, a C-N point of 93.degree.
C., and an N-I point of 240.degree. C. The IR spectrum of this compound is
shown in FIG. 21.
Example 39
40 g of a compound having the following formula was prepared in the same
manner as in Example 35, except for using 32 g of
trans-4-n-pentylcyclohexane carboxylic acid chloride instead of 31 g of
trans-4-n-butylcyclohexane carboxylic acid chloride.
##STR47##
This compound had a nematic liquid crystal phase, a C-N point of
105.degree. C. and an N-I point of 249.degree. C. The IR spectrum of this
compound is shown in FIG. 22.
Example 40
41 g of a compound having, the following formula was prepared in the same
manner as in Example 35, except for using 33 g of
trans-4-n-hexylcyclohexane carboxylic acid chloride instead of 31 g of
trans-4-n-butylcyclohexane carboxylic acid chloride.
##STR48##
This compound had a nematic liquid crystal phase, a C-N point of
107.degree. C., and an N-I point of 239.degree. C. The IR spectrum of this
compound is shown in FIG. 23.
Example 41
A liquid crystal composition was prepared by blending 90 parts by weight of
a commercially available nematic liquid crystal composition, ZLI-1132.TM.
(a product of Merck), and 10 parts of the tolan compound of the present
invention prepared in Example 35. The properties of the liquid crystal
composition are shown in Table 4.
The properties of the liquid crystal composition, ZLI-1132.TM., were as
follows:
NI point: 72.degree. C.
.DELTA.n: 0.138
Viscosity: 27.9 cP
Vth: 1.83 V
Examples 42-46
Liquid crystal compositions were prepared in the same manner as in Example
41 from 90parts by weight of the liquid crystal composition. ZLI-1132.TM.
and 10 parts by weight of the tolan compounds of the present invention
prepared in Examples 36-40. The properties of these liquid crystal
compositions and the chemical formulas of the tolan compounds of the
present invention used for these compositions are given in Table 4, which
also shows the corresponding data for the liquid crystal composition of
Example 41 and the properties of the liquid crystal composition
ZLI-1132.TM..
As can be seen from Table 4, the tolan compounds of the present invention
increase the N-I point and double refractive index (.DELTA.n) of the
liquid crystal compounds which contain these compounds.
TABLE 4
__________________________________________________________________________
Viscosity
N-I Point
.DELTA.n
(cP) Vth (V)
Example No.
Chemical Formula (.degree.C.)
at 25.degree. C.
at 20.degree. C.
at 25.degree. C.
__________________________________________________________________________
41
##STR49## 86.6 0.149
29.5 1.90
42
##STR50## 79.5 0.145
29.1 1.89
43
##STR51## 87.3 0.150
30.1 1.88
44
##STR52## 85.8 0.149
28.9 1.82
45
##STR53## 87.7 0.148
29.0 1.85
46
##STR54## 86.5 0.147
29.7 1.84
ZLI-1132 72.0 0.138
27.9 1.83
__________________________________________________________________________
The tolan compounds of the present invention can increase the N-I point and
double refractive index (.DELTA.n) of a liquid crystal composition and,
when the compounds have an electron attractive group, such as cyano group
or halogen atom, for the terminal group R.sub.1, exhibit a decreased
threshold voltage Vth. The liquid crystal composition comprising the tolan
compound of the present invention, therefore, has excellent
characteristics as a liquid crystal material, and the liquid crystal
display device using this liquid crystal composition has a wide
temperature range and a wide visible angle and can be operated a low
driving voltage. In addition, because the tolan compounds of the present
invention has sufficient compatibility with various other compounds, they
can be used to improve the characteristics of liquid crystal compositions
by using in combination with a number of other liquid crystal materials.
Obviously, numerous modifications and variations of the present invention
are possible in light of the above teachings. It is therefore to be
understood that, within the scope of the appended claims, the invention
may be practiced otherwise than as specifically described herein.
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